Development of the free-living nematode, Turbatrix aceti, as a model system for aging studies will continue, particularly with regard to simplifying the culture medium. The properties of the enzyme, enolase, purified from both young and old T. aceti, will be compared. Pure "old" enolase consists of "altered" molecules compared to the "young" enzyme. The former has a reduced catalytic ability and is more heat sensitive. Comparisons will be made of SH groups, amino acid composition and antigenic properties. "Young" and "old" enolase will be sequenced to the extent necessary to prove or disprove the idea that enzymes are altered during aging by changes in amino acid sequence. A small peptide has been found which is loosely bound to phosphoglycerate kinase. The peptide causes aggregation of the enzyme molecules in buffers of low ionic strength. This aggregation factor will be purified and its role in the regulation of phosphoglycerate kinase will be studied. Any changes in "old" enzyme due to the factor will be explored. Protein turnover studies in aging T. aceti will be continued. Specifically, the effect of age on the half-lives of isocitrate lyase, enolase and phosphoglycerate kinase will be determined. BIBLIOGRAPHIC REFERENCES: Aging and the alteration of enzymes (a review). Rothstein, M. Mech. Age. Dev. in press, (1976). A heat-stable factor which aggregates 3-phosophoglycerate kinase from Turbatrix aceti. Gupta, S.K. and Rothstein, M. Arch. Biochem. Biophys. in press, (1976).